1. Technical Field
This Patent Document relates generally to charge pumps that supply regulated output voltage VOUT, including sensing VOUT.
2. Related Art
A charge pump circuit uses an input voltage to generate an output voltage that is higher than the input voltage. For example, a charge pump voltage doubler supplies output voltage 2x the input voltage. Charge pumps can be operated within an actively controlled control loop to regulate output voltage within a target output voltage band.
The current consumption and efficiency of the charge pump is a function of the ratio of the time that the charge pump is disabled to that of the charge pump is enabled, and the current consumption of the output voltage sense network which provides the feedback to the active control loop. The ratio of the time that the charge pump is disabled to that of the charge pump is enabled is a function of the regulation band, the external output load, the losses of the charge pump, the internal output load (sense network & leakages) and the charge pump operating frequency.
If the sense/feedback network draws significant current when the charge pump is disabled, more frequent enabling is required, resulting in an efficiency loss. For example, in light current-load conditions (such as driving a capacitive load), the total power consumption of a regulated charge pump can become dominated by pump output loading due to the regulator feedback/sense network.